Presently available tampons consist of an inner absorbent core covered by a fluid permeable wrap. The wrap permits fluid to enter the tampon but restrains fluid flow from the tampon. The wraps are made from a variety of fibers, including blended natural and synthetic fibers. For instance, U.S. Pat. No. 4,056,103 describes a wrap made from a blend of cotton, rayon, polyester, and superabsorbent fibers.
The fibers for the web material used as the wrap are generally non-woven. The fibers are held together in the web by either a resin bond or a pressure/temperature-set fuse bond. U.S. Pat. No. 4,305,391 describes a tampon having an absorbent core with two fluid permeable wraps. The inner wrap is partially fluid absorbent to aid in minimizing withdrawal forces and to aid in the prevention of reverse flow. The pore size of the outer wrap is greater than that of the inner wrap to facilitate rapid passage of fluid. The outer wrap is preferably of a lower loft and basis weight than the inner wrap when superabsorbent fibers are employed. Suitable inner wrap fibers are described as meltblown polyolefins, meltblown polyolefin-pulp mixture and polyesters. Suitable outer wrap fibers are spunbonded polyolefins, polyesters, and the like. The inner wrap is laid directly on the outer wrap and heated to fuse in random the contact areas between the two layers of material.
Resin bonding fibers to form the web fabric is described in U.S. Pat. Nos. 4,391,869 and 4,551,143. The non-woven, air-laid fabric is formed predominantly of textile length, synthetic, resilient fibers of staple length. The references describe the bonding solution characteristics as providing less than 180 percent solution pickup and more than 15 percent dry solids add-on.
There are problems, however, with resin bonding and heat fuse bonding of fibers for tampon wraps. These problems include additional manufacturing requirements to evaporate the moisture from the web and unsatisfactory resin performance in sealing the web. Heat fusing thermoplastic fibers also presents problems, including insufficient fusing of fibers as well as overfusing of fibers. Insufficient fusing results in a weak web while overfusing results in a stiff web. These methods of bonding also limit tampon production processing because the web material separates or pulls apart at high processing speed.
An improved tampon is needed with a powder bonded wrap that permits rapid manufacture of tampons having a high absorbance capacity and a lower probability of leakage.